Abrasive and polish compound



United States Patent Qfifice 3,042,509 Patented July 3, 1962 3,042,509 ABRASIVE AND POLISH COMPOUND Paul W. Soderberg, Howell, Mich., assiguor to Bruce Products Corporation, Howell, Mich., a corporation of Michigan No Drawing. Filed Nov. 27, 1959, Ser. No. 855,515 4 Claims. (Cl. 51-305) This invention relates to an abrasive composition and more particularly to an abrasive composition in solid form having a water-soluble binder.

It has been a long standing practice when lapping, buffing and polishing stones in the lapidary and gem making art to use a powdered abrasive mixture consisting of an abrasive material mixed with water. This abrasive mixture has been applied to the work or to a rotatable lap or buffing wheel by means of a brush and then reapplied at frequent intervals as the abrasive is dissipated.

There are several drawbacks to this method. For instance, it is very wasteful of abrasive material, the abrasive which is only loosely adhered to the buff or lap is quickly dislodged as the work is applied to it. Also, it is difficult, particularly for the amateur, to estimate the amount of abrasive needed for a job and consequently a larger amount of abrasive mixture than is needed is frequently prepared, the excess being disposed of as a waste material. Such waste is significant because the abrasive is relatively expensive. The abrasive-water mixture also is disadvantageous in that it creates a clean-up problem. The wheel throws the abrasive into the surrounding media, necessitating the use of protective clothing by the operator and in general dirtying the adjacent area.

It has long been known in the polishing of metals, plastics and other materials that superior finishes are obtained when lubricating materials are used in conjunction with polishing abrasives. In the polishing of metals, such lubricants as stearic acid, tallow, parafiine, waxes and similar materials are used as the bond and lubricant. This type of bond must necessarily have a fairly high melting point in order to hold the abrasive and lubricant together at room temperature. When buliing metals with such compositions, the friction generates sufficient heat to raise the temperature of the work and lubricant above the melting point of the lubricant so that at operating temperatures, the lubricant is liquid.

Attempts have been made in the past to use such binders for abrasives usedin gem polishing compositions. However, in the process of polishing gem stones, such polishing compositions are impractical for several reasons. With small stones it is difiicult to apply suificient pressure to generate enough heat to melt the bond. The gem stone being polished is usually attached to a dop stick by means of a special wax so that it can be held against the buff or lap for processing. Temperatures high enough to melt a grease type bond also melt the dop wax, allowing the stone to fall off the dop stick before the lapping or bufling operation'can be completed. Temperatures high enough to melt a grease type bond will frequently cause certain types of gem stones to split or fracture. Further, grease type bonds or lubricants may work their way into minutecrevices in certain types of stones and become almost impossible to remove, thus leaving the stone discolored or with a streaked efiect.

Also, grease bonds or lubricants must be removed from the work with solvents such as gasoline, carbon tetrachloride or similar materials which are both dangerous and disagreeable to handle. Polyethylene glycols have been blended with abrasives to produce metal buffing and polishing products that are easily removed with water.

Such products have been formed with varying melting points and varying degrees of hardness. However, they have lacked one of the most important characteristics necessary for producing a high lustrous finish on either metal, glass or gem stone because they have not provided the lubricating properties that are so essential in producing a lustrous finish.

It is, therefore, an object of this invention to provide an abrasive composition in solid form, having a watersoluble binder that will have the lubricating ability to produce much higher finishes than heretofore possible except by the use of extremely fine abrasives with the resultant long and 'tedious processes necessary to produce such a finish without lubrication.

It is also an object of the present invention to provide an abrasive composition for lapidary and the like in solid form.

Another object of the invention is to provide an abrasive composition having a water-soluble binder.

A further object is to provide a binder which is nonstaining.

Another object is to provide a binder having a consistency such that it will provide a base for an abrasive to be effective for polishing, bufiing or lapping of such materials as gem stones, rocks, crystals, glass, plastics, dental compositions and the like.

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the phraseology or terminology employed herein as it is for the purpose of description and not of limitation.

The composition of the present invention comprises a uniform mixture of essentially three ingredients: a powdered abrasive material, a solid, water-soluble polyethylene glycol, and a solid, water-soluble ester of polyethylene glycol.

It has been found that a blend, or combination, of a polyethylene glycol with a polyethylene glycol ester of a fatty acid will have excellent lubricating properties when combined with a suitable abrasive material while ret aining the other necessary characteristics such as consistency and water solubility. It has been further discovered that the lubricating characteristics may be increased or decreased to suit varying requirements, such as type of abrasive and nature of the surface to be polished, by varying the proportions of polyethylene glycol to polyethylene glycol ester. Also other faotors such as hardness and melting points may be varied according to the molecular weight of the polyethylene glycol and polyethylene glycol ester used.

The composition may be provided in any desired form, however for convenience of use, it may be cast .into tubes formed of cardboard or other suitable material. Such tubes may be torn away adjacent one end to expose a portion of the composition for application to a lapping or bufiing wheel. As the abrasive composition is worn down, additional amounts may be exposed until the tube is entirely used up. This technique protects the unused portion of the composition against contamination and also permits it to be applied without soiling the hands of the operator.

While the present invention will be described in connection with abrasive compositions for lapidaries and gem makers, it will be readily appreciated that similar compositions may be prepared for applied fields such as for use with dental compositions, crystals for electronics, lenses for optics and like applications.

The proportions of the ingredients in the abrasive composition are preferably from 588% by weight of abrasive and from 12-95% by weight of binder. The binder preferably comprises from 2080% by weight of poly 3 ethylene glycol and from 20-80% of the polyethylene glycol ester.

The abrasive mateiral may be any finely divided or powdered material suitable for the intended use of the abrasive. composition. For example, "a variety of polish ing, bufiing or lapping abrasives may be employed to provide abrasive compositions for dental work, optics, lapidaries, or the preparation of crystals for electronics. For use in connection with lapidary, the abrasive may be, for example, finely divided tin oxide, cerium oxide, alumnum oxide, rouge, chromium oxide, silicon carbide, boron carbide or diamond.

Commercial grades of polyethylene glycol, which are preferred from the cost standpoint, are usually formed by the addition of ethylene oxide to ethylene glycol or water. The polyethylene glycol structure may be written The characteristics of the particular glycol are derived from the many ether linkages and the terminal hydroxyl groups.

The polyethylene glycols useful With the present invention are, in general, the high molecular-weight compounds. Such compounds are water soluble and are solids at room temperature. Consequently, they are useful as binding agents or carriers for the abrasive materials. The useful molecular-weight range is from about 500 to 10,000. Of course, it will be readily appreciated that useful solid polyethylene glycols could be prepared, if desired, by blending a low molecular-weight liquid poly glycol with a high molecular-weight solid polyglycol to obtain a resultant solid product.

The properties and specifications of the preferred polyethylene glycols are given in the following table:

tend to form liquid esters when "a polyethylene glycol having a molecular-weight of about up to 500 is used. This fact should consequently be considered upon the selection of a suitable ester.

The fatty acid used in the preparation of the ester may be, for example, stearic, lauric or oleic acid. The stearic acid esters of polyethylene glycol are preferred due to their properties of excellent color, odor, and stability. The stearates are all solids, ranging from soft solids to hard waxes and thus are well suited for use as binders. Useful stearates are given in the following table by way of example:

TABLE 2 Saponifi- M .P Solubility Ester cation Form C. in

number Water Polyethylene glycol mon- 61*70 Soft solid 37 Soluble.

ostearate (avg. mol. weight of P.E.G., 570-630). Polyethylene glycol mon- 41-49 Wax 42 D0.

ostearatc (avg. mol. weight of P. E. G., 950 1,05 Polyethylene glycol di- 65-74 .d0 Do.

stearatc (avg. m weight off. E. G., 950- 1,050 Polyethylene glycol mon- 2736 .do 46 Do.

ostcarate (avg. mol. weight of P. E. G., 1,300l,600). Polyethylene glycol dl- 49-58 do Do.

stearatc (avg. mol. weight of P. E. G., 1,300-1,600).

The examples which follow are representative of abrasive compositions useful in lapidary and gem making.

TABLE 1 Average molecular weight 9501,050 500-600 1,300- 1,900- 4,200- 7,000 9,000-

Physical appearance Freezing point, C 38 38 45 50 56 59 60 Flashpoint, F 490 430 490 510 515 515 520 Fire point, F 580 470 590 590 590 60 600 Specific gravity at 25/25 C l. 117 l. 200 1. 210 1. 211 1.212 1. 212 l. 212 Viscosity at; 210 F., centistokeshn 17-20 14-18 25-32 40-54 150-210 470-700 1000-1250 Freezing range, C 36-39 38-l 43-46 47-50 5457 56-59 60-64 Water solubility at 25 C APHA color (25% by weight in aqueous solut n) max 25 25 25 25 50 50 Acidity (as acetic acid), percent max 0. 025 0.025 0.025 0.025 0. 025 0.025 0.025 Basicity (as N aOH), percent max 0. 025 0.025 0.025 0.025 0.025 0. 025 0.025 pH of 15% by volume aqueous solution 4. 5-7. 5 4. 57. 5 4. 5-7. 5 4. 5-7. 5 4. 5-7. 5 4.5-7. 5 4.5-7.5

1 Wax-like solid. 2 Complete.

The useful polyethylene glycol esters are preferably esters of a fatty acid of at least 6 carbon atoms. The polyethylene glycol esters are prepared by converting the polyethylene glycol to its mono-ester or diester through its primary alcohol groups.

The preparation of these polyethylene glycol esters can be carried out most simply in a steam-jacketed soap kettle that is equipped with a stirrer. Generally, a whiter and more uniform product can be obtained if an autoclave is used and the reaction carried out under reduced pressure. It is often advisable to agitate the solution with carbon dioxide; the gas acts as an entraining agent for water and may be used either with or Without vacuum. As examples of catalysts, 0.1 to 0.2 percent of sulfuric acid or toluene sulfuric acid by weight of the total charge can be added. Temperatures between 120 and C. for 4 to 6 hours are usually adequate to complete the catalyzed reaction. Esten'fication will also occur at 200 to 220 C. without a catalyst.

It is of course necessary that the ester be water soluble and be a solid at room temperature.

The saturated fatty acid mono-esters and diesters of all of the polyethylene glycols are solids at room temperature. However, the unsaturated fatty acid derivatives The procedure used in the formulation of the examples comprised first heating the polyethylene glycol and the ester at a temperature of between F. to F. until these ingredients melted and blended together. The abrasive material was then added and the composition mixed to a. smooth, uniform consistency. Care was taken to assure that all of the small lumps of. abrasive were broken up and dispersed in the bond. Each composition was then cast into a tubular mold and allowed to cool to room temperature whereupon it was ready for use. In some instances a. small amount of pigment was added to provide an identifying color.

Example I Parts by weight Polyethylene glycol (av. mol. wt. 1300-1600) 22.50 Polyethylene glycol monostearate (av. mol. wt. of

Polyethylene glycol monostearate (av. mol. wt.

Having thus described my invention, I claim:

1. A method of lapidary polishing comprising the steps of applying to a butting element a composition which is a solid as aplied and which consists essentially of the following constituents:

6 Constituent: Percent by weight Abrasive to 88 Binder 12 to95 said binder consisting essentially of:

Polyethylene glycol 20 to 80 Polyethylene glycol ester 20 to 80 both of said binder ingredients being solid and soluble in Water at room temperature, contacting the buffing element with a lapidary stone so that the binder serves also as a lubricant to yield a shiny bright surface on the stone, and Washing the stone with water to remove the composition.

2. A lapidary polishing composition for application to a butting element consisting essentially of the following constituents:

Constituent: Percent by weight Abrasive 5 to 88 Lubricating binder 12 to 95 said lubricating binder consisting essentially of:

Constituent: Percent by weight Polyethylene glycol 20 to 80 Polyethylene glycol ester 20 to 80 both said glycol and said ester being water soluble solids at I'DOH'I temperatures 3,042 o 5 of PEG. was 570-630) 20.00 Cerium oxide 60.00

Total 100.00

Example III 5 Polyethylene glycol (av. mol. wt. 4200-4800) 25.00 Polyethylene glycol monolaurate (av. mol. Wt.

of P.E.G. was 950-1050) 70.00 Rouge 5.00

Total 100.00

Example 1V Polyethylene glycol (av. mol. wt. 1900-2300) 65.00 15 Polyethylene glycol oleate (av. mol. wt. of P.E.G.

was 1300-1600) 17.00 Chromium oxide 18.00

Total Example V I Polyethylene glycol (av. mol. wt. 1300-1600) 7.50 Polyethylene glycol distearate (av. mol. wt. of

PEG. was 1300-1600) 7.50 Aluminum oxide 84.50 Ultraman'ne blue pigment .50

Total 100.00

Example VI Polyethylene glycol (av. mol. wt. 1300-1600) 20.00 Polyethylene glycol monostearate (av. mol. wt. of

PEG. was 1300-1600) 2000 Silicon carbide 60.00

Total 100.00

3. The composition as claimed in claim 2, further characterized in that the polyethylene glycol ester is an ester of a fatty acid having at least six carbon atoms.

4. The composition as claimed in claim 2, and further characterized in that the ester is a polyethylene stearate.

References Cited in the file of this patent UNITED STATES PATENTS 2,548,582 Boak Apr. 10, 1951 2,649,362 Fowler Aug. 18, 1953 2,681,274 Young June 15, 1954 2,696,151 Ellis Dec. 7, 1954 2,765,223 Candee et al. Oct. 2, 1956 2,829,035 Doughty Apr. 1, 1958 2,980,524 Morton Apr. 18, 1961 

2. A LAPIDARY POLISHING COMPOSITION FOR APPLICATION TO A BUFFING ELEMENT CONSISTING ESSENTIALLY OF THE FOLLOWING CONSTITUENTS: 